Glandular breast tissue volume by magnetic resonance imaging in 100 healthy peripubertal girls: evaluation of clinical Tanner staging

Background: Appearance of glandular breast tissue may be difficult to distinguish from fat tissue by palpation, especially in obese girls. To our knowledge, validation of the clinical assessment of pubertal breast stages by magnetic resonance imaging (MRI) has never been performed. Our objective was to report normative data of glandular breast tissue volume and validate the clinical evaluation of pubertal breast staging by MRI of breast tissue and to evaluate circulating reproductive hormone levels and estrogen-dependent transabdominal ultrasound (TAUS) parameters as markers of glandular breast tissue. Methods: Glandular breast tissue volume quantified by MRI and breast stage evaluation was performed in 100 healthy peripubertal girls. Circulating levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), inhibin B, and estradiol were measured by immunoassays. Ovarian volume, uterine volume, and endometrial thickness were assessed by TAUS. Results: Glandular breast tissue volume was positively associated with Tanner stages ( r = 0.858, P < 0.001). The sensitivity and specificity of breast palpation to detect presence of glandular breast tissue using MRI as gold standard were 96 and 95%, respectively. The best parameters to distinguish prepubertal girls from girls with breast development were: LH (area under the curve (AUC) by receiver operating characteristic analysis = 0.871), inhibin B (AUC = 0.847) and estradiol (AUC = 0.830). Conclusion: Clinical palpation reliably detects the presence of glandular breast tissue.